Mobile global positioning satellite (GPS) navigation units are integrated in many portable smartphones that are operated by users riding in vehicles, or are sometimes configured as portable, dedicated, stand-alone, navigation units that are removably mounted in the vehicles, or are sometimes configured as built-in navigation units permanently installed in the vehicles. As is conventional, each such navigation unit is operative for locating a real-time position or current geographic location of a vehicle with triangulation techniques utilizing a plurality of orbiting satellites, and for displaying a map in the environment around the vehicle and/or turn-by-turn directions, together with the real-time position of the vehicle based on map information that is stored in advance. Prior to a trip, the navigation unit typically searches for, and displays, an optimal route to a destination, and provides traveling directions or route maneuvers, such as make a right turn, make a left turn, or go straight (make no turn) before the vehicle reaches each intersection or crossroads of the route. The navigation unit typically estimates the arrival time to the destination based on various factors, such as toll avoidance, street and highway posted speed limits, the total length of the route, etc.
As advantageous as such navigation units are, the estimation of the arrival time could be improved, especially in the common situation depicted in FIG. 1, wherein a vehicle at point A is traveling, for example, at a posted speed limit of 50 mph, along a route or highway having a plurality of lanes, e.g., lane 1, lane 2, and lane 3, toward an intersection I. If the vehicle wishes to make a right turn at the intersection I, then the vehicle enters lane 1 and, as shown, the vehicle speed may, for example, be slowed down to 10 mph to avoid any pedestrians in the illustrated pedestrian crossing, after which the vehicle may accelerate to a speed of 20 mph and proceed toward the point D. If the vehicle wishes to make a left turn at the intersection I, then the vehicle enters lane 3 and, as shown, the vehicle speed may, for example, be slowed down to 30 mph, after which the vehicle may continue at the speed of 30 mph and proceed toward the point C. If the vehicle does not wish to make a turn at the intersection I, but instead, wishes to go straight through the intersection I, then no matter which lane the vehicle is in, it continues at the same speed of 50 mph toward the point B.
Thus, as shown in FIG. 1, the vehicles in lanes 1, 2 and 3 have different actual speeds right before the intersection I. If the estimation of the arrival time is based on the posted speed limit of 50 mph, then it would not be accurate if the vehicle makes a turn at the intersection I. Alternatively, if the estimation of the arrival time is based on averaging all the actual speeds of all the lanes, i.e., 10+50+30=90/3=30 mph, then, again, the estimation of the arrival time to a destination would not be accurate, because the estimation is using an average speed calculated for all the lanes, and not the actual speeds in each of the various different lanes that are intended for different vehicle maneuvers at the intersection I.
Greater accuracy could be achieved by installing traffic speed sensors in each individual lane, but the extra components required by this solution is very costly to install and maintain. Relying on a GPS navigation unit itself to distinguish among the lanes is not available, because the GPS navigation unit does not have the required resolution to distinguish the location of one lane relative to another lane. Thus, it is not possible to precisely calculate the arrival time, or to optimize the shortest and quickest route to the destination without differentiating the different route speeds on different lanes intended for different vehicle maneuvers at the intersection I, which is of special interest to public safety (PS) personnel, such as first responders, who must respond to an emergency and must arrive at an incident scene along an optimal route as quickly as possible. Accordingly, there is a need to accurately estimate the arrival time, and optimize the route, to a destination, taking into consideration the different actual speeds in the lanes that are intended for different vehicle maneuvers at an intersection.
Skilled artisans and practitioners will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and locations of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The method and system components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.